Hackers rally to support WikiLeaks: Top 5 recent attacks

In an effort nicknamed "Operation Payback," a loose association of hackers called "Anonymous" has been targeting the websites of companies and organizations that have cut ties with WikiLeaks by overwhelming their sites with traffic, prompting them to shut down. Twitter and Facebook have blocked accounts for Anonymous, citing the illegality of their attacks as a terms-of-service violation. WikiLeaks' Facebook and Twitter accounts remain up and running.

“Of course, Anonymous is expected to keep creating new accounts as quickly as Facebook and Twitter squash them; it’s a bit like Whack-a-Mole or doing battle with a hydra, in that sense,” said social media news website Mashable. "Fighting Anonymous is a task we wouldn’t wish on anyone."

Below are some of the most notable attacks.

Mastercard and Visa

Mastercard was the first credit-card company to come under attack by hackers, and attacks on Visa soon followed – both launched in retaliation for the companies’ refusal to process donations to WikiLeaks. At various points Wednesday, parts or all of their websites were down, MSNBC reported.

NPR reported Thursday that WikiLeaks’ payment processor, Iceland's DataCell ehf, is preparing to sue both companies for their decision to block the funds, which it claimed is costing the company money.

"It's difficult to believe that such a large company as Visa can make a political decision," [CEO Andreas] Fink said in a telephone interview from Switzerland. In an earlier statement, his company had defended the WikiLeaks, saying that "it is simply ridiculous to think WikiLeaks has done anything criminal."

Paypal

Paypal, which stopped accepting payments for donations to WikiLeaks, was another one of the early victims of hacker attacks. Its blog was down earlier in the week and its main website was inaccessible for several hours Wednesday, according to Computer World. Access was sporadic into Thursday morning. Because Paypal relies on people being able to log in to its site, the company is taking a financial hit from the attacks.

According to Reuters, a spokesman for the group of hackers confirmed that it was executing attacks on Paypal, among others.

Swiss bank Postfinance

The Swiss bank Postfinance, a financial branch of the Swiss postal system, has been struggling to stay online as well after it shut down one of the key WikiLeaks bank accounts.

According to Fox News, Postfinance spokesman Alex Josty said the website “buckled under a barrage of traffic” on Tuesday but that the attacks have eased up. "It was very, very difficult, then things improved overnight," he told the AP. "But it's still not entirely back to normal."

Swedish government

Reuters reported that the Swedish government’s website was down overnight Wednesday. Sweden has issued an arrest warrant for Assange.

The New York Times also reported that the websites of the Swedish prosecutor’s office and the lawyer representing the women involved in the accusations against Assange were down at various points. (Editor's note: The original version used the term "charges" when it should have used "accusations.")

Sarah Palin

Former vice presidential candidate Sarah Palin has been a vocal critic of WikiLeaks, and hackers are fighting back. Computer World UK reported that her personal website was down Thursday morning local time and in an email to ABC news, said that her and her husband’s credit card information had been hacked.

The attacks come only a week after Palin … said the Wikileaks founder, Julian Assange, should be hunted down in the way armed forces target the Taliban and Al-Qaeda.

In an outburst on Facebook, Palin had branded Assange “an anti-American operative with blood on his hands”.

After the attack on her site, Palin wrote: “This is what happens when you exercise the First Amendment and speak against [Assange’s] sick, un-American espionage efforts.”

Hackers have also hit websites belonging to WikiLeaks critics such as US Sen. Joe Lieberman, an independent from Connecticut, according to Computer World.